Does anyone know what one might use to connect a Bluetooth transmitter to the main outs from my Rane Empath to a Bluetooth receiver on my home stereo on another floor? How to send a signal wirelessly in other words.

google for 'wireless RCA transmitter' and you'll find plenty of transmitters that work. Simply plug a spare output from your mixer (rec/booth) into the send box and the output from the recieve box goes into a spare input on your reciever/amp